Buckles are well-known devices for connecting and securing objects. Many well-known buckle designs have been previously described.
A simple patent by Payant (U.S. Pat. No. 3,999,251) illustrates the three parts of a buckle. Payant describes an invention with a belt tongue and a buckle bracket and a locking device.
Coupling patents that describe a tongue passing into a bracket include Mallek (U.S. Pat. No. 5,865,562), Mcleod (U.S. Patent Publication No. 2010/0122411) and Levine (U.S. Pat. No. 4,886,297). Mallek describes a tongue for attachment of dry wall that inserts into a bracket affixed to a substrate. McLeod describes a tongue that fits into a tieplate within a bath. Furthermore, Levine describes a skateboard bracket employing a tongue inserted into a bracket. As illustrated in the prior art, it is known that complementary shape couplings are prone to failure if torque is applied to the base of the tongue perpendicular to the axis of insertion. Furthermore, the cited couplings are prone to failure if a withdrawal force is applied to the tongue, as the cited couplings employ a variety of weak linear locking mechanisms.
Another buckle principle is a locking mechanism. The function of stabilization of the coupling of a tongue and a bracket by means of a more sophisticated locking device acting perpendicular to the line of draw of the tongue has been developed in the class of coupling mechanisms called bayonet mounts. Imanari et al. (U.S. Pat. No. 5,554,503) describes a bayonet mount for a camera lens that uses the bayonet mount to engage bayonet tabs into the mount main body. Ludwig (U.S. Pat. No. 4,307,954) and Fuchi (U.S. Pat. No. 4,660,953) further employ a plurality of tabs on the lens marginal portion to permit the lens to be axially inserted into the body opening. However, a disadvantage of bayonet mounts is the space occupied by the mount itself. A circular tongue results in a coupling requiring a large volume.
Prior art attempting to overcome the deficiencies of bayonet mounts is described in Shadhauser (U.S. Pat. No. 6,893,282), which uses a rectangular tongue in combination with a circular tongue. When the rectangular tongue is inserted the groove, it is rotated to provide a locking mechanism that is perpendicular to the line of draw. However, as with most bayonet mounts, the tongue can be withdrawn easily once the bayonet mount is rotated back to an orientation aligning the tongue with the groove.
Rotation in locks can also be seen in seatbelt buckles such as described in Thorsel (U.S. Pat. No. 4,394,808). The tongue in this case is a flat spring that clips against the bracket by virtue of a ramp and a release feature. Although the tongue is removable, the strength of the locking mechanism is only as strong as the spring in the tongue. Application of a force or a torque to the base of the tongue will also rotate the clip feature of the tongue to be less than perpendicular to the locking feature of the bracket. This leads to a failure in the coupling when the strength of the spring becomes less than that of the force applied.
Improved seatbelts and belt mechanisms are described in Falb et. al (U.S. Pat. No. 7,797,803), Shimizu (U.S. Pat. No. 5,274,890) and Murai (U.S. Pat. No. 5,113,556). However, a common problem with the disclosed belt mechanisms is the lack of internal stability afforded by an internal locking mechanism between a guiding open track and an immovable feature of the bracket. While Murai uses a track open at the insertion end of the tongue whose axis is parallel to the axis of insertion, the coupling is weakened by integrating the locking mechanism into the tongue. Accordingly, there is a need for a buckle system that provides strong support in a multitude of directions and which is not susceptible to separation without specific action taken by the user. Furthermore, there is a need for the buckle system to be compact and without requiring undue size or wasted space. Finally, an efficient buckle system is desired for use with portable electronic devices.